The pigs will join a very short list of gene-modified animals that you can eat. It’s a short list because such animals are expensive to create, face regulatory barriers, and don’t always pay off. For instance, the US took about 20 years to approve a transgenic salmon with an extra gene that let it grow faster. But by early this year its creator, AquaBounty, had sold off all its fish farms and had only four employees—none of them selling fish. Regulations have eased since then, especially around...